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| Moderated by: Greg Fletcher |
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| 907 Cylinder Head | Rating: 
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| Posted: 07-01-2011 01:46 pm |
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1st Post |
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carl.bedlington Member
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We all know that the 907 engine was years before its time, especially for a 1972 production engine. We all strive to make improvements if not for performance but just reliability, with modern day technology and materials we opt for likes of electronic ignition, forged pistons etc. But one thing I cannot find any informtion on is improvements for the cylinder head other than larger St Steel valves and the later zeus head. Wanting to retain the original look but striving for performance and most importantly reliability. Can the cylinder head be brought into the 21st century with the addition of 'valve stem oil seals' and 'Beehive valve springs'? Has anyone replaced the valve guides with the addition of valve stem oil seals? Surely this would be a good thing to do? I have also been hearing and reading lots of rave reviews on the use of 'Beehive valve springs'; apparently due to the design they have a reduced resonance (the main reason double valve springs are used) therefore a single lighter spring can be used to do the same duty. With 16 valves to operate not only would this greatly reduce the energy absorbed to turn the cams it would put a lot less stress on the cam belt. I would love to hear anyones experience or comments on either of the above. Cheers Carl
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| Posted: 07-01-2011 03:17 pm |
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2nd Post |
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Lash Russell Member 
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Hi Carl, I'm no expert but the addidtion of viton valve seals is available, look on the JHPS store. It is part of the Stainless valve upgrade, I'm definitely going to do it. I don't know about the beehive springs but there are valve spring upgrades as well. Maybe someone who has had these installed can elaborate. Lash
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| Posted: 07-01-2011 07:43 pm |
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3rd Post |
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Ramp Member
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Is there any machining required when upgrading the valves and installing valve seals ?
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| Posted: 07-01-2011 08:24 pm |
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4th Post |
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Greg Fletcher Administrator 
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Yes, you will need to do some machine work to do a proper upgrade on a Jensen Healey head. The larger intake and exhaust valves need to be fitted to the head and the head will need to be reamed for the oversized guides. This is not a big deal for a competent machine shop. If you want a performance head, you should get some porting done. Richard at West Coast Racing Heads in Reseda, California is an expert on the JH head and can do whatever you want dependent on how much you want to spend. The later Lotus Zeus head with water cooled exhaust guides would be the ultimate upgrade over the original head. Garry Kemp in the UK could probably set you up with one that has Nibron valve inserts and Colsibro guides, which is what Garry says they run in F1. It's very trick, but the price for a state-of-the-art head on a Lotus engine is pretty steep.
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| Posted: 07-05-2011 05:19 pm |
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5th Post |
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JodyKerr Member 
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Carl, If you are looking for technology beyond the norm in JH circles I would highly recommend checking out what the Lotus folks are doing. The lotus folks (in general) do a lot more racing and because of that spend more time modifying their engines. Jody
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